Structural studies of decomposition in Fe-x at.%Ga alloys

ecomposition in Fe-x at.%Ga alloys subjected to different thermal treatments has been investigated by high-resolution X-ray and neutron diffraction for 12 < x < 25. Quenching suppresses the formation of a D0(3) structure in favor of a high-temperature disordered bcc (A2) structure. By contrast, annealing produces a two-phase mixture of A2 + D0(3) for 14 < x < 20 and a fully D0(3) phase for x = 25. Temperature dependent studies revealed that phase separation occurs below 650 degrees C on cooling for x = 20, where a notable radial line broadening develops. The splitting of the (2 0 0) and (0 0 2) Bragg peaks observed along the respective transverse directions indicates that the samples are composed of multiple crystal grains, slightly tilted with respect to each other. (C) 2007 Elsevier B.V. All rights reserved.